ML20093M282

Requests Review & Approval of Several Issues Re NUREG-0737 Requirement Implementation Concerning post-accident Sampling Sys,Identified as Open Items in Recent Insps

ML20093M282
Person / Time
Site:	Byron, Braidwood, 05000000
Issue date:	10/15/1984
From:	Danni Smith, Danni Smith COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737 9309N, NUDOCS 8410220041
Download: ML20093M282 (14)

Text

M.yEM

~

- l: M]f O* 1/

'+

m m.

y"

~

r e,

-j f One First Nathnet Plan, Chiergo;ilhnois -

s

s. \\ G T Addr:ss Reply is: Post Offica Box 767 )

. s' 4 f"'. Chicago. Illinois 60890

~

tJ O"~'

^

qs

^

- t i

a-y r

4 October 15,.1984-a Mr. Harold'R. Denton,1 Director s14 1.

~ ~

Office of. Nuclear

ReactorJRegulation U'S. Nuclear Regulatory Commission l Washington;,DC 20555

.Su'bject:, Byron' Generating-Station: Units 1 and 2.

~

~

Braidwood. Generation. Station Units 1 and:2 m.

Post' Accident..Sanspling System 2'

iNRC Docket No. 50-454/455 and 50-456/457

^

. Reference'(a):

T. R. Tramm letter to H..R. Denton dated. September 26,.1984:

i

dear'Mr.sDenton:

This i~s to request-review and approval of several issues in connection with our implementation:at Byron'and Braidwood Stations "of requirements setJ forth ~in NUREG-0737.

.These issues have been

identified as;open items in.recent_I&E' Inspections'at Byron-W.~

Station.

L Attachments-1 through~8'to.this_. letter each present a:

+

~

ceparate area. for review as follows:.

i Attachment l:' -Discusses a proposed empirical determination i

k,

-accident.Liodine and particulate sampling.

of line loss correction factors for post F~

i 1

Discusses shielding for iodine sampling in i

'=-

conjunction with -the calculatons presented.

U, in Reference (a).

' Attachment 3:

' Requests' waiver.for Main Steam Line Monitor 1

y displays Requests a waiver for use of low range channel of the Wide Range Gas Monitor in

. ~ <

release rate' calculations.

j u' :

Requests a: waiver for Wide Range Gas Monitor displays.

h*,

O x

4

~.: -

r[ - }{ Attachment-6:

D,iscusses Heat Tracing on Sample Lines.

Attachment.7:

Requests a Waiver for Containment High Range Radiation Monitor Calibration. :- Contains Proposed' Replacement Pages to the FSAR Reflecting Use of the Noble. Gas Monitor and the Containment High-Range Radiation Monitor Calibration.

Please address further questions regarding this matter to this office.

One signed original and fifteen copies of this letter and the attachments are provided for NRC review.

oif s,

trulylQ 9

av d H. Sn h

Nuclear Licensing Administrator Attachments cc:' Byron - Resident' Inspector J. Streeter - RIII

'9309N l

Q(

j-4 ATTACHMENT 1 Byron Nuclear Station Unit.1

.u Empirical Determination of Line Loss Correction Factors for. Post Accident. Iodine and Particulate Sampling - Wide Range Gas Monitoring Land Containment Air Sampling System s

. NRC Region III ' inspection reports 50-454/84-33, 50-455/84-26 and s

50-454/84-54, 50-455/84-37 Eon Byron Station raise the issue of empirical 1 determination.of line loss correction factors for post naccident. iodine and particulate sampling.

These specifically refer

.toL yron's, Wide Range Gas Monitor and Containment Air Sampling B

, Systems to-date.

These. inspection reports make specific reference to1NUREG-0737 section II.F.1, Attachment 2.

The Region III inspectors-have taken the position that such empirical line 1 css correction" factors'are necessary.

' Commonwealth Edison's review of NUREG 0737 reveals no specific or implied requirement for such empirical determinations.

The only i

source of such a requirement.is contained in Regulatory Guide 1.97

.Rev.-3, May 1983, in a tabular footnote.

The Byron FSAR commits Edison to revision 2 of this Regulatory Guide.

The imposition of

. revision 3 requirements is, therefore, not appropriate in terms of

-the Byron operating license.

The> imposition of empirical determinations relating the post accident (ie-degraded core in the 0737 context) source terms is not

technically feasible at this. time.- Neither the industry nor the NRC 1 avelprogressed :far 'enough in the on-going research into degraded 4

h; core source term behavior to quantitatively specify iodine and

' particulate chemical and' physical characteristics in sufficient detail for;thisipurpose.

.This-research has been directed at the establishment of a technical state of knowledge sufficient to quantitatively model the relatively insensitive, macrocosmic interactions germaine to large scale' fission product distribution and behavior (pertinent to

containment failures) as~a. function of time.

The time scales have typically been on the order of hours or tens of hours.

Little or no available work has been published that is directly applicable to the much more sensitive arena of small scale interactions on short time

' frames' associated with' sampling.

For example, the detailed chemical species associated with iodine alone are as much a matter of speculation as hard data.

The effects of species prevelance and behavior, quantitatively, on line losses for sample lines with large length to diameter _ ratios has not been investigated.

Similar arguements apply to the detailed physical characteristics of the various iodine species and to the chemical and physical nature of Other-sampled species.

As a result of this, it is not feasible to establish a proposed source term for empirical determinations that has any firm basis in existing technical knowledge.

@q 3

g.

? ;

'~'

m.

- is

..n

\\

-ATTACHMENT..#1 (Continued)-

.. LSimilarly, fit is not feasible to establish such~a-source term

.for either. analytical evaluations cn: for any kind of cross calibration with readouts from noble gas monitors.. In the-latter case,.one"might

- postulate;that degraded core research should allow the-noble gas releases (to be1 correlated with the iodine =and particulate releases on a

. macrocosmic level..This argument has an element of validity for-any.

G+

given degraded. core scenario.. : However, -it -fails to stand :up -when the-

-full' spectrum of..such scenarios is considered.

The ratio, for example,>

.ofanoble gases to<other fission products. released to the containment-is

.by;no means1a constant for these scenarios.

9 i

Commonwealth Edison therefore proposes to delay any empirical (determination of sampling line losses until such time as the. ongoing Hindustry.and/or NRC research programs develop reasonably definative data

~

" sufficient for.the development of the necessary source term.

Given the 4

current rate of progress-in this area we do not believe that an undue

-time.will pass before this work comes to fruition.

In-the interim, Commonwealth Edison will place the sampling systems into service and

' maintain them in-accordance.with the applicable technical specification-requirements.

a l

+

a lt i

m -

(4;p. ~ ;&..

~ a

~.

+

ATTACHMENT 2

~

f.

[';

Source Term to be Used -tcr Gaseous Effluent: Streams-

~

ENUREG-0737, Table II.F.1-2 specifies a-source. term to be employed in l~

. assessing?the-shielding. envelope for gaseous effluent streams.

As

' applied toJByron; Station,.this-would pertain to the Wide Range Gas x.

_. Monitoring. System.

The source -term-cited has been judged to be substantially more. conservative -than' is?necessary for safe operation.

l Commonwealth Edison has therefore proposed an alternate source term based on-conservative but more realistic assessments.

The use of more

realistic > assessments is expectedLto enhance the effective and timely acquisition'of samples in thelunlikely event of a degraded core accident.

t s commonwealth Edison, la:s an active participant in the Industry

~

Degraded Core' Program, (IDCOR) has detailed analyses of a variety of degradedLcore scenarios which have been performed for the Zion Station.

Insan-effort to develop a source term for this application Edison

-selected'a full core melt scenario based on a transient-initiator coupled with azfull' loss.of.all A.C. power and a full loss of all auxiliary

-feedwater capability.

The IDCOR program has treated a number of

' scenarios.for Zion and.this' selection is considered a worst case, baselineLevent.

The source term from the IDCOR program was scaled up

-from Zion's power level to Byron's and additional margin was added to

. account-for possible variations in containment failure mode details.

Under the conditions of the scenario,. releases into'the auxiliary building -would not readily_ reach the: stack since the fans in the ventilating system would be-inoperable.

Tnis would result in substantial-

' fission -product attenuation 'viatserosol settling.

However, to develop the. source term, an air flow in the auxiliary building' comparable to post (accident,~ fan supplied flow was' assumed.

This insures a rapid sweep of

. fission ~ products to the monitoring system.

The' fission product concentrations were calculated and appropriate dose levels at the sample panel;were:then derived.

a Edison believes that this alternative source term, although conservative, is substantially more effective in assessing the doses at the panelithan the' source term in NUREG 0737.

-In reference (a) Commonwealth Edison requested permission to employ the alternate' source term instead.

T

?

The calculations' forming the basis for this request were submitted

..with1 Reference (a). to Reference (a) contains an error.

~

Part 5 of thatl attachment should road:

5.

Assume Charcoal'is 10% effluent for Iodines.

1.04E O uCi/cc x.90 = 0.936 mC1/cc Iodine Source Term 9'09N 3

7

~,

L

C :.

~

d ATTACHMENT 3 Main Steamline Monitor Displays A permanent waiver is requested for main steamline monitor displays to acknowledge the acceptability'of main control room displays which include:

1.

One RM-23 dedicated digital display for each train of four detectors reading in mR/Hr and located in the main

. control' room.

-2.

Recording by the RM-ll digital data system of detector

-readings in mR/Hr and located in the main control room.

The detector readings in mR/Hr are used by station personnel in a station-procedure to calculateJthe release rate from the steam generator atmospheric relief and the safety relief valves.

' A permanent waiver is requested.

- 9009N

O J~

4

.v

> i_-

/

ATTACHMENT 4 Low' Range < Channel oftthe Wide Range-Gas Monitor A waiver is requested for not including.the low range channel lof,Lthe-GA; Technologies,~Inc. Wide Range Gas Monitor used on the Auxiliary Building Vent Stack in:the release rate calculations of II.F.1, Attachment 1. Clarification'4(b).

NUREG-0737 has.been interpreted to_not require'the low range channel for post accident monitoring since it-is the normal operation range and.the mid and high

range channels envelope post accident conditions.

NRC I&E personnel

.haveLindicated that inclusions of the low range channel may not be

.necessary.

A permanent waiver is requested.

If it is ruled that it is required, a variance for time is requested so that calculations and associated methodology for. quantifying the post accident noble gas release rate can be prepared..

l

cr- -

ATTACHMENT 5 Wide Range Gas Monitor (WRGM) Displays A permanent waiver is requested from the requirement that the monitor display and recording be in terms of uCi/cc of Xe-133 equivalent or actual noble gas mix.

The variance is requested to acknowledge the acceptability of main control room displays which include:-

1.

One RM-23 dedicated digital display for each WRGM capable of reading uCi/cc of pseudo noble gas for each of the three channels.

2.

Recording by the RM-ll digital data system of detector readings in uC1/cc of pseudo noble gas.

The variance is requested because Commonwealth Edison Company's GSEP A Model is based on the use of a pseudo noble gas, GR-999, having E

= 0.8 MeV per disintegration and a E max = 1.68 per disintegration.

The weighted sensitivities to this psuedo noble gas will be programmed into the RM-80 (WRGM microprocessor).

Calculations in the RM-80 using channel sensitivity and counts per minute will yield uCi/cc of psuedo noble gas.

In addition, stack flow rate is available to the RM-80.

The WRGMs RM-23 digital display located in the control room will be able to retrieve from the RM-80 the following informatin:

1.

Counts per minute.

2.

Concentration of psuedo noble gas (uC1/cc-GR-999).

3.

Stack flow rate (CFM).

Time dependent correction factors are required to account for the aging of the actual mix relative to the psuedo noble gas.

The manual application of the release rate correction factors to the above items 2 and 3 will yield estimates of concentration of actual noble gas mix and release rate, respectively.

In conclusion, a manual method for estimating the release rate of actual noble gas mix, based on information extracted from the RM-80 at the RM-23 and transferred to the Technical Support Center, upon request, and release rate correction factors already located at the TSC, will be available so that TSC personnel can estimate the noble gas release rate.

A permanent waiver is requested.

9309N i

' E

.4 g

1 f

ATTACHMENT.6 2

6

HEAT TRACE.ON SAMPLE PIPING There-currently is no heat trace on a short length of sample

'=lineiin the Ccntainment Air Sample Panel nor.on the sample lines leading to'the Wide Range Gas Monitor.

Appropriate Heat Tracing will be: installed upon both of these lines prior to exceeding 5% power.

f.

l

f'

e 9 '[,

ATTACHMENT 7 CONTAINMENT HIGH RANGE RADIATION MONITOR CALIBRATION c

.NUREG 0737, Table II.F.1-3 requires " calibration for each detector for at least one point per decade of range between 1R/hr. and

>103 R/hr."

Each Containment High Range Radiation M nitor used at Byron was calibrated by the' manufacturer at approximately 200 R/hr., 2000 R/hr., and 20,000 R/hr. rather than each decade between 1 R/hr. and 103 R/hr.

The manufacturer performed necessary testing to comply with~other pertinent sections of Table II.F.1-3 of NUREG-0737.

Factory calibrations are supplemented by "in situ" calibrations (source calibrated at 2 points less than 10 R/hr. and electronically calibrated at each decade from 0.1 R/hr. to 108 R/hr.)

Byron Station concludes that the calibrations performed on g

the Containment High Range Radiation Monitors are adequate in demonstrating the proper operability of the monitors as intended by NUREG 0737 and is therefore requesting a deviation from the

" word-for-word" NUREG 0737 requirement for a factory calibration for each decade between 1 R/hr. and 103 R/hr.

J 9309N f

~

11 -

~

ATTACH?!ENT 8 B/B-FSAR -.

E.30

ADDITIONAL ACCIDENT-MONITORING INSTRUMENTATION (II.F.1)

POSITION:

1.

- Noble Gas Effluent Monitor (II.F.1-1) -

a. Auxiliary Building Vent Stack Two General Atomic Company wide-range monitors will be installed the auxiliary building vent stacks (final release points), one monitor.

per stack. The monitor has a range for radioactive gas concentration of 1 x 10-7 uCi/cc to 1 x 10+5 uCi/cc. The monitor is designed to meet IE requirements and is qualified to IEEE 323-1974. The wide-range gas monitor meets the requirements of Table II.F.1-l' of NUREG-0737. The monitor includes the followin : two isokinetic nozzles, one for normal conditions operating at 2 ftg/ min and one 3

- for high range conditions operation at 0.06 ft / min. sampling rack-(reference discussion of II.F.1-2); sample conditioner, operating only at high range conditions to filter out large concentrations of radiolodine and particulates; and the wide-range gas detectors assembly, consisting of three radioactive' gas detectors, a low-range detector (Model Number RD-52-61), a mid-range detector (RD-72-01) and a high range detector (Model Number RD-72-02). Each monitor system has a microprocessor which utilizes digital processing techniques to analyze data and control monitor functions. Control room readouts include an RM-23 remote display module for all monitor parameters.

1.

The calibration techniques and procedures including the

- energy dependence of the detectors will be provided to meet the requirements of NUREG-0737.'

2.

The monitors will receive power from ESF buses.

3 Post - Accident plant release rate calculations will be made using Station procedures and vent stack monitor readings..

q S

L.

y g-z..

12 -

.1 b.

Main'Steamline

~ Two General Atomic Company RD-10B detectors will be provided 1 for each of the four main steamlines upstream of the safety and relief valves. The range of the monitor is 1 x 10-1 uCi/cc to 1 x 104 L uci/cc. The monitor is designed to meet IE requirements and is -

' qualified to IEEE 323-1974. The monitors will be mounted external to the main steamline piping and corrections made for the loss of low energy gammas.

The detectors are connected to local mounted microprocessors that collect and store data. Main control room mounted remote readout modules are connected directly to the microprocessors to provide information to the operator during and following an accident. The main steamline detectors readout continuously in

.mR/hr. Conversion of detector readings to release rate (uCi/sec) sis accomplished through the use of a station procedure.

2.

Sampling and Analysis of Plant Effluents (II.F.1-2)

The General Atomic Company wide range gas monitor includes a' sampling rack for collection of the auxiliary building vent stack particulate and radiolodine samples. Filts.r holders and valves are provided to allow grab.-

sample collection for isotopic analysis in the stations; counting rooms.

The sampling rack is shielded to minimize personnel exposure. The sampling media will be analyzed by a gamma ray spectrometer which utilizes a Ge(LI) detector. Filter cartridges will be reverse blown with air to purge interferring noble gases.

9 L

g 3.

Containment High-Range Radiation Monitor (II.F.1-3)

In accordance with NUREG - 0737 the following required documentation items as listed in the NUREG are listed with the response for the Byron /Braidwood Stations:

11.

The description of or name of manufacturer and model number of the monitors; General Atomic Company Model RD-23 high range radiation detector, Model RM-80 microprocessor and RM-23 remote display unit.

2._

Verification that the monitors meet the specifications of Table II.F.1-3; REQUIREMENT The capability to detect and measure the radiation level within the reactor containment during and following an accident.

Comply.

RANGE 1R/hr to 107 (gamma only).

Comply.

RESPONSE

60 kev to MeV photons, with linear energy response + 20% for photons of 0.1 MeV to 3MeV.

Instruments must be accurate enough to provide useable information.

Comply.

REDUNDANT A minimum of two physically separated monitors (i.e., monitoring widely separated spaces within containment).

Comply..

DESIGN AND QUALIFICATION Category 1 instruments as described in Appendex A except as listed below.

We assume Category I refers to Regulatory Guide 1.97, Rev. 2. The design of the high range containment monitors complies with the Category 1 instrument requirements of Regulatory Guide 1.97, Rev. 2 e

L

.r;

- /

14 -

SPECIAL j

CALIBRATION In situ calibration by electronic signal

~' ^

substitution is acceptable for all range decades above 10R/hr. In situ calibration for at least one decade below 10R/hr shall be by means of calibrated radiation source.

The originallaboratory calibration is not an acceptable position due to the possible differences after in situ installation. For high-range calibration, no adequate.

sources exist, so an alternate was provided.

A General Atomic Company RT-11 portable calibration source will be used for the first decade requirement.

AdditionaHy, electronic operability check is provided by l

means of an Internal current source corresponding to 5

10 R/hr.

SPECIAL ENVIRONMENTAL QUALIFICATION Calibration and type-test of representative specimens of l

detectors at sufficient points to demonstrate linearity 6

throJgh all scales up to 10 R/hr. Prior to initial use, calibration of coil detector for at least one point per 3

decade of range between IR/hr and 10 R/hr will be certified.

1 The radiation detectors have been tested over a rane of 43.5 kev to 4.5 MeV and at 5.17 x 10 R/hr. Sufficient l

6 tests he.ve been performed to demonstrate linearity.

Celibrations prior to initial use are performed by the manufacturer at 200 R/hr,2000R/hr, and 20000R/hr to satisfy special environmental qualification calibration requirements.

3.

Verification that the monitors will be operable on June 15,1984; The requirement, as stated in Enclosure 2 of NUREG-0737, of the implementation four months prior to issuance of an operation license will be met.

4.

A plant layout drawing showing the location of the monitors.

Figures E.30-1 shows the locations of the detectors in both the Unit I and Unit 2 containments.

4 4

9

%